1. Field of the Invention
The present invention relates to a polyethylene terephalate (P.E.T.) off-centre neck bottle and its manufacturing method, and more particularly to such a P.E.T. bottle in which the neck of the released bottle is off-centre.
It is easy to control the pouring of liquid from such an off-set neck bottle. Also liquid can be quickly poured from the bottle.
2. Description of the Prior Art
Previously, plastic bottles have been manufactured by extrusion blow moulding from P.E. (polyethylene), P.P. (polypropylene) and P.V.C. (polyvinylchloride). However, these materials can release poisonous substances. They are not accepted by the FDA. The extrusion blow moulding process produces runners, which have to be manually trimmed. This is a waste of time and manpower. The runners can also cause environmental problems.
In the nineteen seventies, a new technology—injection stretch blowing—was invented. In injection stretch blowing, the material used is P.E.T. (polyethylene terephalate). It, is approved by the FDA for food packaging P.E.T. is more transparent, durable and lighter. Before long, most plastic bottles were made from P.E.T. The process for making a P.E.T. bottle is different from extrusion blowing. In the production of a P.E.T. bottle a preform must first be made by injection moulding. The preform must then be heated to the desired temperature, and next moved to a blowing mould for blowing into a bottle. The shape of a P.E.T. bottle is usually round, square or oval.
As mentioned, the production of the bottle as such must be preceded by the injection moulding of the preform. For reliable blowing, this should be placed in the centre of the blowing mould. Normally, in the production of a P.E.T bottle, the neck of the bottle is designed to be positioned centrally at the top of the bottle. Only by use of special machinery and extra labour, can an off-centre neck bottle be produced, therefore it is very rare to see off-centre neck P.E.T. bottles on the market. Nevertheless, if liquid is stored in central neck bottles, they must be tilted to a substantial angle for pouring, which is not easy. Moreover, it can be difficult to control the amount being poured out. Also the liquid tends to drip down the neck of the bottle. In the case of a large bottle containing oil, especially without a table to place it on, the whole bottle has to be lifted for pouring from it. Generally such a bottle is inconvenient to use.